A vehicular air conditioning device used in an automobile and the like includes a heater core which is a heat exchanger for heating, an evaporator which is a heat exchanger for cooling, an air mixing space for mixing warm air that has passed through the heater core and cool air that has passed through the evaporator, and an air mixing damper for changing a mixing ratio between the warm air and cool air in the air mixing space. In such a device, a mixing ratio between the cool air and the warm air is changed by adjusting a pivot amount of the air mixing damper, and thus air with a desired temperature is obtainable.
For the aforementioned device, from a view point of supplying air with uniform temperature distribution to the respective seats inside the vehicle, it is important for the air mixing damper to uniformly suppress air leakage between a heater core side and an evaporator side. Specifically, when the respective parts of the air mixing damper are different in sealing performance, the mixing ratio between the warm air and the cool air may be changed locally. This may cause an imbalance of temperature distribution in the air discharged into the inside of the vehicle.
A technology for suppressing such air leakage is known, for example, from Patent Document 1 listed below. In the vehicular air conditioning device disclosed in Patent Document 1, the rim of a plate-like air mixing door (an air mixing damper) is made in contact with a sealing wall that is integrally formed in an air conditioning case. In such a vehicular air conditioning device, the sealing performance between the heater core side and the evaporator side by the air mixing door is enhanced.